Gear lubricant



United States Patent 3,250,711 GEAR LUBRICANT Curtis L. Early, Alton, Ill., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 6, 1964, Ser. No. 350,103 3 Claims. (Cl. 25237.2)

This invention relates to improved gear oils comprising a blend of two selected petroleum stocks as the base for the "extreme pressure gear oil additive mixture of the present invention, which functions synergistically.

It is well known in the lubricant art that one of the most effective and economical additive combinations for use in gear oils is a mixture of lead naphthenate and a sulfurized fatty oil. Gear oils containing this additive mixture have been used successfully for years in commercial applications such as steel mills, power generating plants,

etc. However, current operating conditions have become progressively more severe due to heavier unit gear loading, higher bulk oil operating temperatures, etc. This results in rapid oxidation of the oil, sludging, coprecipitation and depletion of the additives mentioned above and general breakdown of the lubricant resulting in severe damage to equipment, increase in repair costs, and loss in time and production.

It has now been discovered that an oil blend consisting of a mixture of 55-85% of a particular high viscosity index bright stock fraction and 45-15% of a high viscosity index mineral lubricating oil, both fractions having both fractions being rich in aromatics, function not only naphthenate and a sulfurized fatty oil or derivative therea viscosity index of at least 80, prefer-ably 90-140 and I of such as sulfurized sperm oil, but the base oil blend acts synergistically to activate the extreme pressure life .of gear oil additive mixture so that it is increased many fold, namely from 1 to 10 times that of commercial gear oils containing lead naphthenate and sulfurized fatty products, and inhibits additive depletion and oxidation of the composition. The manner in which the oil blend of the present invention functions in the manner described is not understood, except for the fact thatin order to produce the desired results, the base oil blend must be carefully selected and blended in specific proportions, each fraction of which must possess the following properties:

(1) the bright stock fraction must be rich in aromatics (570%) and have a viscosity index of at least 80, preferably between 90 and 110 and is obtained during the refining of mineral oils from the short residue after the distillate fractions have been removed. The short residue is dewaxed and deasphalted and if desired solvent and clay-treated. The raffinate which remains after this treat- -ment is called bright stock. v

The brightstocks should have the following range of properties:

TABLE I.-1 RoPERTIEs OF BRIGHT STOCKS Viscosity, SUS,

100 F. l'250, usually 12501l,000, preferably 1500-3500.

iercentnaphthenes 35. Percent parafiins At least 60.

. 9. may vary up to 30%, or more. A typical lead naphthenate,

T 3,250,711 Patented May 10, 1966 TABLE IIL-SPECIFICATIONS FOR TYPICAL MID-CON- TINENT BRIGHT STOCKS Unfiltered Filtered Gravity, API, minimum 25.5 24. 5 25. 5 Color, 8+ Dark green 6. 7 Pour point, F, maximum 10 10 10 Flash, F., minimum 540 580 545 F re, F., minimum..- 615 655 610 Vrscos ty, SUS, 210 F 150-170 200-215 150-160 Viscosity index, minimum 9O 90 The other portion of the oil blend is a high viscosity index lubricating oil distillate fraction and specifically is a refined distillate fraction having a viscosity index of at least 90, preferably 90-110, an SUS viscosity at F. in the range of 100-600, and containing substantial proportions of heterocyclic aromatics such as sulfur-containing aromatics (2-l0%) such as benzothiophenes, dibenzothiophenes, thiophenacenaphthylenes, thiophenophenanthrenes, thiophenopy-renes, etc. Such a typical petroleum fraction will be referred to as fraction (Y) and such a fraction derived from an East Texas Crude has the following properties:

Viscosity, SUS, at 100 F. 250

Viscosity index 90-95 Analysis (incremental ultraviolet absorption):

Monoaromatics, percent l4 Polyaromatics, of which 13-17% are di-arornatics containing thiophenic structures, e.g., benzoand dibenzothiophenes, percent 21 Polar-containing resins, percent 3 Essentially ba1ancesaturates.

Base blends which are particularly preferred are:

60% Bright stock (unfiltered-Table III) 40% HVI oil fraction (Y) 70% Bright stock (12% aromatics) 30% HVI oil fraction (Y) The additive combination which is synergistically activated, stabilized and its depletion inhibited by the base blend described comprises of a mixture of 1-10% (preferably 2-5%) lead naphthenate and 110% (preferably 3- 6%) by weight of sulfurized long chain fatty oil product such as sulfurized sperm oil.

The lead naphthenate utilized in the'lubricant can be prepared from naphthenic acids obtained in the refining of petroleum, particularly the naphthenic acids derived from lubricating oil fractions. Moreover, the naphthenic acids can contain some non-saponifiable mineral oil which prepared from lubricating oil naphthenic acids having a non-sflponifiable content of about 23%, has a PhD content of roughly about 20% by weight. Lead naphthenate prepared from naphthenic acids essentially freed from non saponicfi-able content will run about 30% PhD content.

The sulfurized fatty material containing -40% sulfur in the molecule can be sulfurized sperm oil (30% S). A sulfurized sperm oil of this type is available from Carlisle Chemical Works as Base 100-8 or 120-S, the latter of which has the following properties:

Sulfur 13.0 percent.

in practically all petroleum oils. Sulfur separation None.

In addition to the two essential additives, a minor amount (15% by weight) of a secondary additive can phenol; bisphenols, e.g. 4,4'-rnethylene (2,6-ditertbutyl phenol), 4,4'-thio bis (2,6-ditertbutyl phenol); arylamines such as phenyl-alpha-naphthylamine or phenyl-beta-naph- I thylamine.

The following examples illustrate the invention;

(I) Base blend (A):

+2.7% lead naphthenate +40% sulfurize d sperm oil (13% S) l polyisobutylene (MW 1200) +5 p.p.m. dirnethyl silicone polymer (200 cs. at

C.) (II) Base blend (B):

+2.7% lead naphthenate +40% sulfurized sperm oil (13% S) +1% polyisobutylene (MW 1200) I +5 ppm. dimethyl silicone polymer (200 cs. at

4 (III) Base blend (A):

lead naphthenate +4.5 sulfurized sperm oil (IV) Base blend (C): V 5 65% Bright stock (40% aromatics) HVI mineral lubricating oil (VI=90, Aromatics 35 +4% lead naphthenate +4% sulfurized sperm oil (V) Base blend (13):

10 65 Bright stock (30% aromatics) 35% HVI mineral lubricating oil (VI=90, Aromatics 30% +25% lead n aphthen-aite 1r +4% sulfurized sperm oil (VI) Base blend (A):

+2.7% lead naphthenate sulfurized sperm oil (13% S) +1% polyisobutylene (MW 1200) 1% polyisobutylene (MW 800) +5 p.p.m. dimethyl silicone polymer (200 cs. at

. The following compositions were subjected to the following tests and the results are shown in Table IV. Tests Oxidation Tests (X) 300 F. Bench Oxidation Test (B0 Test).In this method 300 ml. of test oil are oxidized in a cylindrical Pyrex glass cell at 300 F. with 5 liters air perhour for 168 hours. No catalyst is used. The relative oxidation resistance of an oil is evaluated by viscosity increase and sludge formation during the test.

Oxidation Test (XX) Modified Turbine Oil Stability Test.This test is a modification of ASTM Method D- 943, Oxidation Characteristics of Inhibited Steam Turbine Oils. In modifying ASTM D-943 for assessing the oxidation characteristics of Macoma blends, the test temperature is increased from 205 F. to 250 F., air instead of oxygen is used, water is omitted, and oil test. life con- 4 stitutes' the number of hours of oxidation required to double the original S.S.U. viscosity at 210 F.

Extreme Pressure Test: (XXX) Timken EP Test (Fed. Stand. method 6505-T) Corrosion Test: (XXXX) Copper Strip "Corrosion T es (ASTMD-130).The Copper Strip Corrosion Test, ASTM D-l30, was used to evaluate the copper corrosivity at 212 F. This test was modified to evaluate also corrosivity of blends toward both copper and steel (A181 1020) at 300 F. The appearance of metal panels 0 after 3 hours immersion at the required test temperature is used as an indication of the corrosive propensity of test oils.

TABLE IV Compositions (X) (XX) (XXX) (XXXX) Percent Mg sludge Percent Pb Mg sludge Max. lbs; Cu cor. at S.S.U. at at end test loss per 10 g. passed 212 F. and 210'F. inc 300 F.

7.0 76 56 20 60-65 Passed. 8 40 18 -65 Do. (VI) 7. 5 45 35 15 60-65 Do. (IA) 60/40 blend of steam refined pet-ro- 8.8 409 347 45, Failed.

leum stock plus mineral lubricating oil VI) containing additive mixture oi (IB) Bright stock plus mineral lubricating 38. 2 277 83 419 40 Do. oil (40 VI) containing additive mixture of (II). I (IC) Same as I but lead snlfonate substi- 510 25 Do.

tuted for lead naphthenate in equal amount. (ID) Same as I but dibenzyl disulfide 19 820 55 D0.

used for sulfurized sperm oil in equal amounts.

Compositions of the present invention can be used as extreme pressure lubricants for various heavy duty equipments operating under severe and adverse conditions of temperature and pressure.

I claim as my invention:

1. An improved gear oil composition consisting essentially of a mixture of two mineral oil fractions of: (1) 5585% of a 90140 VI Bright Stock having an aromatic content of at least 5% and (2) 15% of a mineral lubricating oil having a viscosity of 100-600 SUS at 100 F., viscosity index of at least 90 and 210% sulfur-containing aromatics of thiophenoiic and benzo thiophene structure and having incorporated therein from about 1% to about 10% each of lead naphthenate and sulfurized sperm oil.

2. An improved gear oil composition consisting essentially of a mixture of two mineral oil fractions of: (1) 85% of a -140 VI Bright Stock having an aromatic content of 570% and (2) 45-15% of a mineral lubricating oil having a viscosity of -600 SUS at 100 F., viscosity index of at least 90 and 210% su1furcontaining aromatics of thiophenolic and benzothiophcne structure and having incorporated therein from about 1% to about 10% each of lead naphthenate and sulfurized sperm oil.

3. The composition of claim 2 containing from about 0.1% to 5% each of polyisobutylene and 4,4-methylene- (2,6-ditert-butylphenol).

References Cited by the Examiner UNITED STATES PATENTS 2,136,391 11/1938 Miller 252-372 X 2,160,293 5/1939 Shoemaker et al 252-45 2,607,732 8/1952 Duchon et al. 25237.2 2,704,745 3/1955 Kopp et al. 252-37.2 2,816,867 12/1957 Moore et al 20819 X 2,932,615 4/1960 Jordan et al 252-45 X 3,018,248 1/1962 Foehr 252-37.2

DANIEL E. WYMAN, Primary Examiner. CARL F. DEES, Assistant Examiner. 

1. AN IMPROVED GEAR OIL COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF TWO MINERAL FRACTIONS OF; (1) 55-85% OF A 90-140 VI BRIGHT STOCK HAVING AN AROMATIC CONTENT OF AT LEAST 5% AND (2) 45-15% OF A MINERAL LUBRICATING OIL HAVING A VISCOSITY OF 100-600 SUS AT 100*F., VISCOSITY INDEX OF AT LEAST 90 AND 2-10% SULFUR-CONTAINING AROMATICS OF THIOPHENOLIC AND BENZOTHIOPHENE STRUCTURE AND HAVING INCORPORATED THEREIN FROM ABOUT 1% TO ABOUT 10% EACH OF LEAD NAPHTHENATE AND SULFURIZED SPERM OIL. 